A thin film transistor (TFT) plays a key role in a display device. As a non-linear switching element, the thin film transistor has been widely applied to a large size LCD display and AM-OLED display.
An active layer of the thin film transistor may be a semiconductor material comprising metallic elements, for example a metal oxide semiconductor material, or a metal-doped semiconductor material. In this case, during etching a metal layer to form a source and a drain, since the active layer comprises metallic elements, this etching will damage the active layer region between the source and the drain. This results in that the design requirements cannot be met, the mobility is reduced, and the performance of thin film transistor is affected.